1. Field of the Invention
This invention generally relates to a color change paint and varnish remover. More specifically, the present invention provides for a paint removal formulation having a color change feature to indicate when the stripping action of the formulation has substantially ceased and is ready for removal. The formulation comprises: at least one penetrant, at least one carrier and at least one colorant whereby the formulation is applied to the target area and as the surface of the formulation dries, the colorant migrates away from the dehydrating surface leaving a finely divided carrier that emits white light. This color change indicates that the stripping action of the formulation has ceased and is ready for the scraping and removal step.
2. Description of the Related Art
The term “paint and varnish remover” as used herein refers to chemical compositions which can strip or remove all types of coatings, such as, paints, lacquers, enamels, varnishes, shellac, polyurethane, epoxies, and other coatings used on substrates such as metal and wood.
Methylene chloride paint strippers have long been the standard for stripper performance. Although effective in stripping action, high volatility shortens the working time for paint and varnish removal, often requiring more than one application when used on thicker accumulations of paint. In addition, the environmental concerns and the potential carcinogenic effects based on lab tests on mice and rats, has led to ever increasing regulations concerning its use.
Other solvents, such as toluene, xylene, methanol, acetone, ethanol in addition to being flammable, are themselves or in various combinations also highly volatile, requiring multiple applications when thick accumulations of paint are to be removed, and therefore suffer because their work life is insufficient to permit complete penetration of the paint layers before drying out.
The use of safer solvents to replace methylene chloride and flammable paint and varnish removers, is well documented in previous patents. N-methyl-2-pyrrolidone (NMP) has long been employed as the main active ingredient in various paint stripper compositions that offer safer alternatives to methylene chloride and flammable solvent compositions. (NMP) costs over four times as much as methylene chloride, and as much as ten times as much as common flammable alternatives, and various attempts have been made by adding less costly components to (NMP) mixtures, while still maintaining removal properties. U.S. Pat. Nos. 4,120,180; 4,749,510; 5,006,279; and 5,015,410 all refer to various combinations of (NMP) and various aromatic hydrocarbons and other additives to maintain removal efficiency and lower overall costs. Unfortunately, such aromatic hydrocarbons are under increasing regulatory pressures as hazardous air pollutants, and their insolubility in water makes them more difficult to remove from the surface by water washing. Furthermore, these aromatic (NMP) blends, using recommended thickeners, primarily of the cellulosic type, suffer from poor sag resistance, especially when sheared by rapid brushing action or spraying. This leads to insufficient thickness of paint and varnish remover to penetrate effectively, before drying out. U.S. Pat. Nos. 4,666,626 and 4,732,695 refer to paint and varnish removers based on oxy hexyl acetate/cyclohexanone compositions, and benzyl alcohol, aromatic hydrocarbon/(NMP) compositions, respectively, which rely on cellulosic thickeners that sag or drip pulling the paint and varnish remover away from the paint surface so that direct contact is lost. The loss of contact destroys penetrability before drying out.
U.S. Pat. Nos. 5,098,591; 5,124,062; 5,167,853; and 5,298,184 refer to paint and varnish removers based on combinations of (NMP) and various citrus terpene solvents. These compositions also contain cellulosic type thickeners, as well as organoclay thickening agents to aid in sag resistance and to control flow. U.S. Pat. No. 5,035,829 utilizes primarily (NMP), acids and alkylene glycol ethers, and relies on cellulosic thickeners, and is used to remove over spray from spray booths. U.S. Pat. Nos. 5,049,300; 5,098,592, and 5,154,848, disclose compositions containing (NMP) and or (BLO) gamma-butyrolactone, and ethyl 3-ethoxyproprionate (EEP) using cellulosic type thickeners to provide thickening and sag resistance.
Thus, there remains a need in the art to provide an effective paint and varnish stripper which has better sag resistance, especially on vertical surfaces, while maintaining stripping effectiveness, along with the lower toxicities, volatilities, and environmental benefits that are outlined in various patents, while avoiding the use of methylene chloride, toluene, methyl ethyl ketone, acetone, methanol or other highly volatile and/or flammable components.
Most traditional strippers containing methylene chloride or other volatile and flammable chemicals such as methanol methyl ethyl ketones, acetone or toluene, and strip paint quickly, but will remove only 1 or 2 layers per application.
In the color change formulations, the natural color of the components fades to off-white when the stripping action has substantially ceased. The addition of a coloring agent, such as a dye or a pigment, to the compositions in the range of up to 2%, will intensify the color change (i.e. a medium green to off-white or a pale green) to signal better to the applicator that removal should begin. In addition, with the advent of modern day safer stripper formulations, the resulting stripping actions tend to be much slower than paint and varnish removers based on methylene chloride, and other volatile, flammable solvents or combinations thereof, so that it is difficult to determine when the striping action is finished.
Furthermore, it is well known in the art, that modern day paints, based on latexes, because of their tendency to buckle, swell and blister cause difficulties in maintaining contact with the layers of paint to be stripped. The stripping agent is pulled away from the surface by the buckled and blistered paint. Often this results in the paint stripper and loosened top layers of paint to drop from the sub-layer of paint producing a loss of direct contact with the paint stripper. The loss of direct contact requires additional application of paint stripper. Thus, there remains a need in the art to provide an effective paint and varnish remover which has better sag resistance, very low odor, a signaling device to indicate the completion of paint stripper action, and an effective way to prevent the excessive bubbling, blistering and swelling that can lead to the types of problems described herein.
Furthermore, despite the present of surfactants and other wetting agents, soaps and the like, it has been proven through experimentation that many of the compositions and formulas fail to loosen the paint layers sufficiently if dried to the point where little or no liquid is present. Therefore, there remains a need in the art for a paint and varnish remover that is removable at any stage wet or dry, even when the remover has totally dried.
It is advantageous if these improvements in the state of the art also has lower volatilities and, environmental benefits that are outlined in various other patents referenced, while avoiding the use of methylene chloride, toluene, methyl ethyl ketone, acetone, methanol, ethanol or other highly volatile and/or flammable components.
The color change feature of the present invention signals the completion of the paint strippers action and indicates the time at which the paint stripper is ready to be removed along with the softened paint layers. The paint and varnish stripper of the present invention is biodegradable, non-flammable, odor free and easily cleaned up with water. It contains no methylene chloride or caustic. It truly clings to vertical surfaces. It removes most varieties of paints and varnishes, which are oil or water-based including latexes, stains, alkyds, and polyurethane. It can be applied on a multitude of interior and exterior surfaces including wood, brick, plaster, metal, marble, masonry, concrete and fiberglass. It also strips significantly more paint than traditional paint strippers.